How to make displacement to effect all the surface?
You need to do several things:


Select your plank and in the Properties panel > Material tab > Settings > Surface > Displacement, enable Displacement Only, otherwise the Displacement node won't give anything.





Give your plank a Subdivision Surface modifier so that it has geometry to move.





Switch to Render mode to see the result, apply the scale of your object so that you have a 1/1/1 scaled object, you'll see that it will go crazy because of your settings.





So just adjust the settings (didn't try to understand all your nodes organization though).